Chemical, biological and respirometry properties of soil under perennial crops fertilized with digestate

A b s tr a c t. The aim of this study was to evaluate the effect of thea digestate which originated fromon a widely cul-tivated perennial crop (Miscanthus giganteus). Cchanges in the physicochemical properties of the soil, the abundance of soil microorganisms, and soil respiration were all assessed. Three types of digestate: fresh in the liquid form, processed - dried and pyrolysed, were tested and compared with mineral fertilization and an unfertilized control. Soil samples were taken in spring 2014, summer 2015 and autumn 2016. In total, 14 variables were analysed: total carbon, hot water extractable carbon, total nitro-gen, C/N ratio, phosphorus, magnesium, potassium, pH, bacteria, fungi, O2 intake, CO2 emission, total carbon mineralized after 7-and 100-day-long respiration. Overall, regardless of the form of the digestate, the chemical parameters of the soil improved, although the extent of the improvement depended on the applied form of the digestate. The highest TC 12.79, N 1.29, K 257.95 and P 149.96 g kg-1 DM were determined in the plots fertilized with biochar. All digestate forms had a positive influence on the bacte-rial DNA abundance, and biochar also affected the abundance of the fungal DNA and the potential carbon sequestration in the soil. Pyrolysed digestate may have a particular value in the fertilization of perennial industrial crops.